/* ----------------------------------------------------------------------
* Copyright (C) 2010 ARM Limited. All rights reserved.
*
* $Date:        15. February 2012
* $Revision: 	V1.1.0
*
* Project: 	    CMSIS DSP Library
* Title:		arm_shift_q15.c
*
* Description:	Shifts the elements of a Q15 vector by a specified number of bits.
*
* Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
*
* Version 1.1.0 2012/02/15
*    Updated with more optimizations, bug fixes and minor API changes.
*
* Version 1.0.10 2011/7/15
*    Big Endian support added and Merged M0 and M3/M4 Source code.
*
* Version 1.0.3 2010/11/29
*    Re-organized the CMSIS folders and updated documentation.
*
* Version 1.0.2 2010/11/11
*    Documentation updated.
*
* Version 1.0.1 2010/10/05
*    Production release and review comments incorporated.
*
* Version 1.0.0 2010/09/20
*    Production release and review comments incorporated.
*
* Version 0.0.7  2010/06/10
*    Misra-C changes done
* -------------------------------------------------------------------- */

#include "arm_math.h"

/**
 * @ingroup groupMath
 */

/**
 * @addtogroup shift
 * @{
 */

/**
 * @brief  Shifts the elements of a Q15 vector a specified number of bits.
 * @param[in]  *pSrc points to the input vector
 * @param[in]  shiftBits number of bits to shift.  A positive value shifts left; a negative value shifts right.
 * @param[out]  *pDst points to the output vector
 * @param[in]  blockSize number of samples in the vector
 * @return none.
 *
 * <b>Scaling and Overflow Behavior:</b>
 * \par
 * The function uses saturating arithmetic.
 * Results outside of the allowable Q15 range [0x8000 0x7FFF] will be saturated.
 */

void arm_shift_q15(
    q15_t* pSrc,
    int8_t shiftBits,
    q15_t* pDst,
    uint32_t blockSize)
{
	uint32_t blkCnt;                               /* loop counter */
	uint8_t sign;                                  /* Sign of shiftBits */

#ifndef ARM_MATH_CM0

	/* Run the below code for Cortex-M4 and Cortex-M3 */

	q15_t in1, in2;                                /* Temporary variables */


	/*loop Unrolling */
	blkCnt = blockSize >> 2u;

	/* Getting the sign of shiftBits */
	sign = (shiftBits & 0x80);

	/* If the shift value is positive then do right shift else left shift */
	if(sign == 0u) {
		/* First part of the processing with loop unrolling.  Compute 4 outputs at a time.
		 ** a second loop below computes the remaining 1 to 3 samples. */
		while(blkCnt > 0u) {
			/* Read 2 inputs */
			in1 = *pSrc++;
			in2 = *pSrc++;
			/* C = A << shiftBits */
			/* Shift the inputs and then store the results in the destination buffer. */
#ifndef  ARM_MATH_BIG_ENDIAN

			*__SIMD32(pDst)++ = __PKHBT(__SSAT((in1 << shiftBits), 16),
			                            __SSAT((in2 << shiftBits), 16), 16);

#else

			*__SIMD32(pDst)++ = __PKHBT(__SSAT((in2 << shiftBits), 16),
			                            __SSAT((in1 << shiftBits), 16), 16);

#endif /* #ifndef  ARM_MATH_BIG_ENDIAN    */

			in1 = *pSrc++;
			in2 = *pSrc++;

#ifndef  ARM_MATH_BIG_ENDIAN

			*__SIMD32(pDst)++ = __PKHBT(__SSAT((in1 << shiftBits), 16),
			                            __SSAT((in2 << shiftBits), 16), 16);

#else

			*__SIMD32(pDst)++ = __PKHBT(__SSAT((in2 << shiftBits), 16),
			                            __SSAT((in1 << shiftBits), 16), 16);

#endif /* #ifndef  ARM_MATH_BIG_ENDIAN    */

			/* Decrement the loop counter */
			blkCnt--;
		}

		/* If the blockSize is not a multiple of 4, compute any remaining output samples here.
		 ** No loop unrolling is used. */
		blkCnt = blockSize % 0x4u;

		while(blkCnt > 0u) {
			/* C = A << shiftBits */
			/* Shift and then store the results in the destination buffer. */
			*pDst++ = __SSAT((*pSrc++ << shiftBits), 16);

			/* Decrement the loop counter */
			blkCnt--;
		}
	} else {
		/* First part of the processing with loop unrolling.  Compute 4 outputs at a time.
		 ** a second loop below computes the remaining 1 to 3 samples. */
		while(blkCnt > 0u) {
			/* Read 2 inputs */
			in1 = *pSrc++;
			in2 = *pSrc++;

			/* C = A >> shiftBits */
			/* Shift the inputs and then store the results in the destination buffer. */
#ifndef  ARM_MATH_BIG_ENDIAN

			*__SIMD32(pDst)++ = __PKHBT((in1 >> -shiftBits),
			                            (in2 >> -shiftBits), 16);

#else

			*__SIMD32(pDst)++ = __PKHBT((in2 >> -shiftBits),
			                            (in1 >> -shiftBits), 16);

#endif /* #ifndef  ARM_MATH_BIG_ENDIAN    */

			in1 = *pSrc++;
			in2 = *pSrc++;

#ifndef  ARM_MATH_BIG_ENDIAN

			*__SIMD32(pDst)++ = __PKHBT((in1 >> -shiftBits),
			                            (in2 >> -shiftBits), 16);

#else

			*__SIMD32(pDst)++ = __PKHBT((in2 >> -shiftBits),
			                            (in1 >> -shiftBits), 16);

#endif /* #ifndef  ARM_MATH_BIG_ENDIAN    */

			/* Decrement the loop counter */
			blkCnt--;
		}

		/* If the blockSize is not a multiple of 4, compute any remaining output samples here.
		 ** No loop unrolling is used. */
		blkCnt = blockSize % 0x4u;

		while(blkCnt > 0u) {
			/* C = A >> shiftBits */
			/* Shift the inputs and then store the results in the destination buffer. */
			*pDst++ = (*pSrc++ >> -shiftBits);

			/* Decrement the loop counter */
			blkCnt--;
		}
	}

#else

	/* Run the below code for Cortex-M0 */

	/* Getting the sign of shiftBits */
	sign = (shiftBits & 0x80);

	/* If the shift value is positive then do right shift else left shift */
	if(sign == 0u) {
		/* Initialize blkCnt with number of samples */
		blkCnt = blockSize;

		while(blkCnt > 0u) {
			/* C = A << shiftBits */
			/* Shift and then store the results in the destination buffer. */
			*pDst++ = __SSAT(((q31_t) * pSrc++ << shiftBits), 16);

			/* Decrement the loop counter */
			blkCnt--;
		}
	} else {
		/* Initialize blkCnt with number of samples */
		blkCnt = blockSize;

		while(blkCnt > 0u) {
			/* C = A >> shiftBits */
			/* Shift the inputs and then store the results in the destination buffer. */
			*pDst++ = (*pSrc++ >> -shiftBits);

			/* Decrement the loop counter */
			blkCnt--;
		}
	}

#endif /* #ifndef ARM_MATH_CM0 */

}

/**
 * @} end of shift group
 */
